I've found out (thank you my dear sister) that there are six different 'traps' in the library. only three doors will lead to the library: one with a blue snake, one with some kind of labyrinth on it and one with a zigzag line with on it a red dot, two green dots and a blue dot. You can then chose from four scrolls on a table. Once you read one, you will fall through a trapdoor. If you try any of the other doors, you get trapped or turned into a pile of sand... however, the effect only lasts a day.